Preheat the oven to 225°F
With a hand or stand mixer and whisk attachment, beat the egg whites on medium speed. Add the cream of tartar and salt, continuing to beat until soft peaks form
Gradually add the sugar and Jello powder, one tablespoon at a time, while beating until stiff peaks form. Add the sugar slowly to prevent deflating the meringue.
Mix until the egg whites are glossy and smooth
Using a 1M piping tip, pipe the meringue into rosettes on a parchment-lined cookie sheet
Bake for 1 hour. Turn off the oven and leave the meringues inside for at least another hour without opening the oven door.
Once cooled and dry, the cookies are ready to enjoy!
